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Invasiveness Assessment - Laurel clock vine (Thunbergia laurifolia) in Victoria

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Plant invasiveness is determined by evaluating a plant’s biological and ecological characteristics against criteria that encompass establishment requirements, growth rate and competitive ability, methods of reproduction, and dispersal mechanisms.

Each characteristic, or criterion, is assessed against a list of intensity ratings. Depending upon information found, a rating of Low, Medium Low, Medium High or High is assigned to that criterion. Where no data is available to answer a criterion, a rating of medium (M) is applied. A description of the invasiveness criteria and intensity ratings used in this process can be viewed here.

The following table provides information on the invasiveness of Laurel clock vine.

A more detailed description of the methodology of the Victorian Weed Risk Assessment (WRA) method can be viewed below:

Victorian Weed Risk Assessment (WRA) method (PDF - 630 KB)
Victorian Weed Risk Assessment (WRA) method (DOC - 1 MB)
To view the information PDF requires the use of a PDF reader. This can be installed for free from the Adobe website (external link).

Common Name: Laurel clock vine
Scientific name: Thunbergia laurifolia

Question
Comments
Rating
Confidence
Establishment
Germination requirements?“Each time [a stem] falls to the ground it takes root” (CRC Weed Management, 2003).
H
M
Establishment requirements?Protected, partly shaded position recommended for horticultural plantings (Bodkin, 1990).
However, pictures of the vine (Starr, 2002), and the types of vegetation that it invades (Starr, Starr & Loop, 2003) suggest that it needs access to light.
ML
MH
How much disturbance is required?Mostly lowland moist disturbed areas; Sparingly adventive along hiking trails or margins of urban areas; spreading vegetatively from planting into nearby disturbed lowland scrub.

Remnant wet forests and coastal river habitat (Starr, Starr & Loop, 2003). Roadsides, pastures and headlands of canefields (CRC Weed Management, 2003). Establishes in highly disturbed natural ecosystems.
ML
MH
Growth/Competitive
Life form?Climbing vine (PIER, 2005).
ML
MH
Allelopathic properties?None found in CRC Weed Management (2003).
L
M
Tolerates herb pressure?Very tuberous root system which can resprout from many dormant buds when cut, but no record of herbivory in CRC Weed Management (2003).
H
M
Normal growth rate?Aggressive…attaining height up to at least 15 m (Starr, Starr & Loop, 2003). Large, aggressive
vine…capacity to smother coastal, lowland rainforest (Csurhes & Edwards, 1998).
H
MH
Stress tolerance to frost, drought, w/logg, sal. etc?Young plants die back when temperatures drop below freezing point. Commonly found in damp areas (CRC Weed Management, 2003), and Bodkin (1990) notes that it is drought and frost tender. Tolerant of one and susceptible to at least two stressors.
L
M
Reproduction
Reproductive systemSeeds, cuttings and fragments of stems and roots (PIER, 2005).
H
MH
Number of propagules produced?Most literature indicates that the vine is sterile, mostly reproducing by vegetative means. However, in Johnson Shire T. laurifolia has been observed growing from seed, which is quite unusual. Images in CRC publication suggest that if seeding were to occur, probably more than 1,000 seeds could be produced per flowering event (CRC Weed Management, 2003).
MH
M
Propagule longevity?Tubers numerous and large, often the size of a 4WD vehicle. Uncommonly produces viable seed and is assumed to reproduce vegetatively most of the time (CRC Weed Management, 2003).
L
M
Reproductive period?Individual patches completely cover several hectares, eventually leading to the destruction of most other vegetation (CRC Weed Management, 2003). Photographs show T. laurifolia forming dense monocultures (Starr, 2002).
H
MH
Time to reproductive maturity?No data available. Mostly known to reproduce vegetatively
M
L
Dispersal
Number of mechanisms?Seeds, cuttings and fragments of stems and roots (PIER, 2005). Contaminated fill. Careless disposal of garden waste. Infestations along riverbanks have been caused by root pieces… being transported by floodwaters (CRC Weed Management, 2003).
MH
MH
How far do they disperse?Can spread from dumping of garden cuttings (PIER, 2005). Also floodwaters (see number of mechanisms) and stem/root fragments. Most propagation is vegetative and some vegetative pieces could be transported km by people and water, but most would be unlikely to disperse more than 200 m.
ML
MH


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